This one's a slight diversion from the project logs so far. There's more to write about with software setup and changes I've made recently for robustness, but I got sidetracked trying to add a scale to measure propane. There's at least one nearly perfect off the shelf device for this - a load cell-based BLE propane tank scale from Flame King. It'd be nearly perfect if I could just hack together a battery eliminator for it, and let the Pi connect to it via Bluetooth for real time propane weight measurement.
All the details of my attempt at that so far are over on my blog: https://www.alexwhittemore.com/reverse-engineering-cots-products-for-your-project/